So I'm just starting to dig into Mocha (for reference, I'm using Hitfilm 3 Pro and the bundled version of Mocha Hitfilm), and I ran into an interesting oddity just now.
I have a composite shot in Hitfilm that I want to roto a mask for. It's in the MPEG-2(? - extension .m2ts) format, so I right-click my clip and select "Open in Mocha". Mocha opens, I set my project paths, etc., and then instead of seeing my clip, I get a blank workspace and no timeline. So I poke around a bit, and it looks like Mocha doesn't support that format, so I go to the Clip tab and Import a format it does recognize; first .mp4, then .wmv
What happens next is really odd. Mocha gives me a dialog box with the clip settings in it, so I click Import, and it adds a new layer to the tab up top with the name of my clip in it, but the workspace is empty except for what looks like half a dotted rectangle in a random color. I can't select anything and the new clip's timeline is still blank.
Eventually, I went back to Hitfilm, exported the composite into an .mp4, imported that .mp4 into Hitfilm, then successfully opened that clip in Mocha and I'm on my way. But it seems strange to me that I can't directly import clips into Mocha. I know I can only launch Mocha Hitfilm from within Hitfilm itself, but I'm wondering if there's any other crippled functionality, and whether my experience just now is a bug or not.